[sonic-saidredis]: Advance submodule (#8153)

Update sonic-sairedis submodule to include below commits:
84fa50a Revert "[vs]: Start syncd by passing context configuration file and global context index. (#832)" (#859)
736dc3b Remove redudnant mention of platform cisco-8000 (#856)
969ad94 Support for cisco-8000 platform for sonic-sairedis/syncd (#823)
1eacd05 [sairedis] Client/Server add support for SAI stats api (#855)
59fedfa [sairedis] Client/Server support SAI fdb flush api (#853)
5c2aaae [syncd] bulk OID remove requires RID (#854)
7da0894 [sairedis] Client/Server support SAI query API (#848)
443ad36 [sairedis] Style refactor cleanup (#850)

Signed-off-by: Suvarna Meenakshi <sumeenak@microsoft.com>